COMPUTATIONAL STUDY OF HYDROGEN DOPING AND EQUIVALENCE RATIO EFFECTS ON THE IGNITION DELAY OF PURE METHANOL UNDER COMPRESSION IGNITION ENGINE CONDITIONS

Methanol is a promising low-carbon fuel for compression-ignition (CI) engines due to its clean combustion and renewable production potential.However, its low cetane reactivity results in prolonged ignition delays, limiting its applications in CI.This study computationally examines the effects of hydrogen doping and equivalence ratio on methanol ignition delay under CI-relevant conditions.Zero-dimensional, constant-volume simulations were performed using Cantera with AramcoMech 3.0, and results were cross-validated with the USC Mech II mechanism.The analysis covered pressures of 20-50 bar, temperatures of 800-1000 K, equivalence ratios from 0.5 to 1.2, and hydrogen fractions up to 30% by volume.Baseline results confirmed strong temperature dependence and pressure-induced acceleration of methanol ignition, with stoichiometric mixtures igniting faster than lean blends.Unexpectedly, hydrogen doping consistently increased ignition delay by 6-8% across conditions, attributed to altered radical competition, reduced carbon-fuel chain branching, and increased mixture heat capacity.Although richer mixtures partially offset this penalty, the inhibitory effect of hydrogen remained evident.These results challenge the common assumption of universally improved reactivity with hydrogen addition and emphasize the need for multidimensional simulations and experimental validation.The findings provide new insights into methanol-hydrogen ignition chemistry and its implications for future CI engine applications.